In a mobile communication system, a radio environment for a radio base station changes as a building is constructed in a surrounding area of the radio base station or an installed situation of a base station in a surrounding area of the radio base station changes. For this reason, a drive test has been performed by an operator to measure and collect a radio environment using a measurement vehicle in which measurement equipment is mounted.
These measurement and collection of the radio environment can contribute to optimizing the coverage of a radio base station, for example. However, there is a problem such that there includes many processes and thus the cost is increased. For this reason, developed in the 3GPP (3rd Generation Partnership Project), which is a standardization project of a mobile communication system, are specifications of MDT (Minimization of Drive Test) which is a technique in which a radio terminal being held by a user is used to automate measurement and collection of a radio environment.
The MDT includes an Immediate-report-type and a Logged-type. The immediate-report-type MDT (hereinafter referred to as an Immediate MDT when needed) is such that a radio terminal in a connected state performs measurement and a result of the measurement (hereinafter referred to as a “measurement result”) is reported to a network together with location information. Here, the connected state is a state where a radio terminal is executing communications. The logged-type MDT (hereinafter referred to as a Logged MDT when needed) is such that a radio terminal performs measurement when a set condition is fulfilled and the measurement result is stored together with the location information and time information as MDT data, and, thereafter, is reported to the network.